This invention relates to the art of nuclear reactor power plants. It has particular relationship to the refueling of the reactors of such plants. In carrying out the refueling, the reactor to be refueled is at the base of a pit in a containment filled with water to a depth of 20 or 30 feet. During refueling, component assemblies of the reactor or from refueling racks are engaged by grippers or grapples of a mast assembly, raised, transported from their position of origin and lowered in the position where they are to be deposited. The component assemblies are highly radioactive and are engaged, raised, transported and lowered under a substantial depth of water. To carry out this operation, there is provided apparatus including a bridge moveable along a track on the containment. A trolley is moveable on a track on the bridge. The trolley carries a mast assembly having a rotatable supporting mast from which the component-assembly engaging-raising-and-lowering means is suspended. This means is sometimes herein referred to as "component-assembly handling mechanism" or "assembly-handling mechanism" or simply "mechanism". With the bridge and trolley at selectably different positions along their tracks, the mast assembly is suspended with the assembly-handling mechanisms at selectably different positions of the area of the pit or of the reactor within the pit.
The mast assembly includes a supporting mast from which the component-assembly-handling mechanisms are suspended. To accommodate component assemblies that are out of position radially, the supporting mast and the mechanisms suspend from it are rotatable in a bearing member secured to the trolley. The mechanisms on the mast assembly include electric and fluid-pressure operable means to which electricity and fluid must be supplied. Electric power is derived from an outlet on the containment. The cable from this outlet through which the power flows extends to the bridge through festoon loops which permit movement of the bridge. From the bridge the cable extends to the trolley where it supplies power to a control console. The electrically operable means on the mechanisms of the mast assembly are connected through wires and other facilities to the control console on the trolley where they derive their power. Typically, the pressure fluid is compressed and derived from a compressor on a bridge and supplied through an air conductor or hose. The air hose extends to the trolley whence it extends to the mast assembly and is connected to the fluid-pressure operable means on the mechanisms of the mast assembly.
Electric conductors may be designated variously as "cables" or "wires". The word "cables" is frequently applied to members which include a number of different electric conductors that conduct different currents and are insulated from each other. At times the word "conduit" is used to describe a tube including a number of wires. Conductors of fluids are often designated as "hoses"; "air hoses" or "water hoses" or the like. In this application and particularly in the claims the words "conductor" or "electric conductor" or "fluid conductor" will at times be used to designate generally cables or wire or conduits which conduct electric current or hoses which conduct fluids.
Since the mast assembly is rotatable relative to the trolley, provisions must be made in the electric and fluid conductors between the trolley and the mast assembly to permit this relative motion. In accordance with the teachings of the prior art the electric and fluid conductors are grouped together, mounted on a support on the trolley and extended to the rotatable mast assembly. To permit relative movement of the mast assembly and trolley a long festoon loop must be interposed in the grouped conductors between the support and mast assembly. It is necessary that this loop have a point of attachment on the support which is high in the apparatus. This is undesirable. In addition, the fluid and electric conductors are subject to twisting when the mast assembly is rotated.
The hoist which raises or lowers the component-assembly-handling mechanisms has cables connected to the mast assembly through swivel joints. The cables are wound or unwound from a hoist drum and remain aligned during raising or lowering. During lowering the fluid and electric conductors connected to the mechansims must be payed out or let out and during raising of the mechanisms these conductors must be retracted. To permit the resulting changes in the lengths of the fluid and electric conductors, these conductors are wound on reels. In accordance with the teachings of the prior art, the mast assembly is rotated relative to the hoist a nd conductor reels. In such a structure the fluid and electric lines turn with the mast assembly. The turning of these conductors limit the rotation of the mast assembly. In addition the conductors may foul the hoist cables.
It is the object of this invention to overcome the difficulties and drawbacks of the prior art.
It is another object of this invention to provide refueling apparatus which shall not require a long festoon loop in the fluid and electric conductors between the trolley and the rotatable mast and in whose operations these conductors shall not be twisted. A third object of this invention is to provide refueling apparatus in whose operation rotation of the mast assembly shall not be restricted by the fluid and electric conductors and fouling of the hoist cables by these conductors on rotation of the mast assembly relative to the trolley shall be precluded.